Conventionally, there have been suggested various methods for facilitating browsing of an electronic book by using a touch panel device (a device having a touch panel display unit, such as a tablet terminal, a smartphone, a personal computer, or the like) (for example, refer to Patent Document 1).
Patent Document 1 describes that, in the case where a visitor continuously touches a certain place of a touch panel display unit for a predetermined time or longer, an enlargement target region around the touched place is set and an image obtained by enlarging the enlargement target region is superposed on the original image and displayed. The image is displayed in this manner, thereby enabling the visitor to visually recognize the original image and an enlarged image of a part of the original image simultaneously and thus enabling an increase in the browsing performance of information displayed in the touch panel display unit.